2. HISTOPLASMOSIS
• Histoplasmosis is an infection caused by a fungus
called Histoplasma Capsulatum.
• The fungus lives in the environment, particularly in
soil that contains large amounts of bird or bat
droppings.
3. It is also known as....
• Cave disease,
• Darling's disease,
• Ohio valley disease,
• Reticuloendotheliosis,
• Spelunker's lung and Caver's disease..
4. General Characteristics
• Dimorphic fungus
- Sexual multi-cellular saprophytic mycelia
- Asexual single-celled parasitic yeast
• Mycelial form most commonly found in the environment.
• Heteroth allic species.
• Tightly Coiled septate hyphae
• Smooth,hyline,spherical
Ascospores
• Globose cleistothecia
• Pear – shaped asci
5. • Condia germinate via non/polar budding.
• Yeast form is the infectious agent in humans.
• Yeast cells have white,thin-walled,oval bodies.
• Form sexual macro – and microconidia
- Also borne by hyphae in the mycelial form.
6. Histoplasmosis - Types
• Two major forms of histoplasmosis
1)Pulmonary histoplasmosis
2)Disseminated histoplasmosis
7. Pulmonary histoplasmosis
• Pulmonary histoplasmosis occurs when
microconidia or mycelial fragments are
inhaled.
• Form lesions in the hilar or mediastainal
nodes.
11. Clinical Manifestations
• Most people who are exposed to the
fungus Histoplasma never have symptoms.
• Fever
• Cough
• Fatigue (extreme tiredness)
• Chills
• Headache
• Chest pain
• Body aches
12. • Symptoms of histoplasmosis may appear
between 3 and 17 days after a person
breathes in the fungal spores.
• In some people, usually those who have
weakened immune systems, histoplasmosis
can develop into a long-term lung infection, or
it can spread from the lungs to other parts of
the body, such as the central nervous system
(the brain and spinal cord).
13. PREVENTION
• Avoid exposure. Avoid projects and activities that
might expose you to the fungus, such as cave
exploring and raising birds, such as pigeons or
chickens.
• Spray contaminated surfaces. Before you dig soil
or work in an area that could harbor the fungus
that causes histoplasmosis, soak it with water.
This can help prevent spores from being released
into the air. Spraying chicken coops and barns
before cleaning them also can reduce your risk.
15. 2.Direct examination
• Smears of sputum or pus are stained with
giemsa or wright stains.
• In tissues,the yeast phase occurs within
phagocytic cells
• The yeast appers as an oval,budding cell
measuring 2-4 µm while in african
histoplasmosis,much larger yeast –like cells(7-
15µm) are seen.
17. 3.Culture
• SDA or brain heart infusion (BHI) agar with
cyloheximide and chloramphenicol are
inoculated.
• The yeast phase is formed in culture at 37°C .
• White cottony mycelial growth containing
large (8-20 µm) thick walled ,spherical spores
with tubercles or finger like projections
appears at 25°C.
18.
19. 3.Serological tests
• Latex aggultination precipitation and
complement fixation tests become positive
two weeks after infection.
• Increase in titre of antibody indicates a
progressive disease.
20. 4.Histoplasmin skin test
• Delayed hypersensitivity test.
• The test is similar to tuberculin test but
antigen used is histoplasmin.
• Histoplasmin is a culture filtrate antigen of
mycelial phase of H.capsulatum.
• A positive ‘histoplasmin skin test’ indicates
past or present infection,but does not
differentiate active and past infections.
21. • Diagnosing histoplasmosis can be
complicated, depending on what parts of your
body are affected.
• While testing might not be necessary for mild
cases of histoplasmosis, it can be crucial in
treating life-threatening cases.
22. Treatment
• Itraconazole is one type of antifungal
medication that's commonly used to treat
histoplasmosis.
• Depending on the severity of the infection and
the person's immune status, the course of
treatment can range from 3 months to 1 year.
• Many people will need antifungal treatment
for histoplasmosis.
23. • Severe infections or disseminated cases of
histoplasmosis require treatment
with antifungal medications.
• Itraconazole
• fluconazole
• amphotericin B
• drug of choice for severe disease are
antifungal drugs that treat histoplasmosis.
